Electric control apparatus for fuel burners



March -17, 1936. L. M. PERSONS 2,034,309

ELECTRIC CONTROL APPARATUS FOR FUEL BURNERS Filed Nov. 17, 1933 2 Sheets-Sheet l a f a w W Mm may M W%% R T d J vfi -1- W m J 9 u n W a w k Z w? i W f 7b E T m WW flllflll 20v v a w 0 w I Q i Q 0 Y 4? -u m 3 m 6 V llll II M w m R w w m 1% Q rm 0 7. M /W r I I I m I. ilk r r MM March 17, 1936, L, M P N 2,034,309

ELEC'JE'RIC CONTROL APPARATUS FOR FUEL BURNERS Filed Nqv. 17, 1933 2 Sheets-Sheet 2 CURRENT 8UPPLY Jaw/v34! .f/awrezzce Z77. firm/u 2/ 171: 5 5 57W 94W Maw/W Jim/21411 Patented Mar. 11, 1936 ELECTRIC CONTROL APPARATUS FOR FUEL BUENEBS Lawrence M. Persons, Des Moines, Iowa, assignor to Penn Electric Switch 00., Des Moines, Iowa,

a corporation of Iowa Application November 11, 1933. Serial No. 698,477 6 Claims. (01. 158-28) The object of my invention is to provide an 7 electric control apparatus for fuel burners which i is simple, durable and comparatively inexpensive to manufacture.

A further object of my present invention is to provide a control apparatus for arfuel burner I which has circuit arrangements for quickly shutting down operation of. the burner when combustion fails after occurring, initial failure of combustion operating to shut down the control apparatus only after a period of time.

Still a further object is to provide control apparatus inwhich a lock-out switch is opened by delayed action actuating means if combustion does not occur, orby a magnetic safety trip mechanism if combustion does. occur but thereafter fails, the safety trip mechanism being energized by contacts of a combustion switch which havethe peculiarity of closing only after the combustion switch moves from cold to hot position and then returns toward cold position, such peculiarity being effected by a frictional mounting for one of. the contacts.

Another object is to provides control circuit for a fuel burner wherein the ignition mechanism is de-energized by an ignition trip mechanism cooperating with a relay in such fashion that regardless of whether the relay is energized or de-energized, the .ignition contacts remain closed but are opened-by the ignition trip mechanism,,th is being possibleonly when the relay is energized and has accordingly moved the ignition contacts to a position where they can be tripped-by the ignition trip mechanism when it is energized.

A further object is to provide the ignition trip mechanism in the form of a magnet attracted armature and contacts, one of which is the arma ture and which is so arranged that after the ignition trip mechanism operates, current no longer flows through it. I

Still a further object is to provide a relay and a running circuit through its entire coil, the safety trip mechanism being energized by connecting it across a part of the relay coil, the relay coil thus acting as an auto transformer for supplying current to the safety trip mechanism.

Still a further object-is to provide a peculiar type of contact mechanism operated by an oscillating element and arranged so that contacts are kept separated from each other when the oscillatingelement moves in one direction, but are engaged and then separated when the oscillating element moves in the opposite direction.

with these and other objects in view my invention consists in the construction, arrange-' ment and combination of the various parts of my device, whereby the objects contemplated are attained, as hereinafter more fully set forth, pointed out in my claims, and illustrated in the 5 accompanying drawings, in which:

Figure 1 is an electrical diagrammatic view of a control apparatus embodying my invention.

Figures 2 to 6 illustrate successive opening and closing positions of various contacts of the com- 10 bustion switch of my control apparatus.

Figures 7 and 8 illustrate successive views in. the operation of the relay switch; and Figure 9 is a simplified diagrammatic illustration of the system.

0n the accompanying drawings, the combustion switch comprises briefly a bimetal coil II for 1 rotating a rod l3 having a ratchet l5 thereon. The ratchet l5 coacts with a leaf spring l'l for swinging it to various circuit controlling posi- 20 tions.

The swinging of the leaf spring I! controls starting contacts ill, ignition trip contacts 12 and safety trip contacts l4.

One of the contacts I4 is mounted on an arm 2| 25 which is frictionally pivoted. An extension l'la. of the leaf spring I! is adapted to actuate the arm 21 and also an arm Zia on which the lower contact I4 is mounted. The parts II, II, it and I! operate as disclosed in the Williams Patent No. 30 1,827,703, ofOctober 13, 1931.

The relay switch' has ignition contacts l6, motor contacts 18 and 20 and holding contacts 22. These are operated by an armature l9 attracted by either one or both coils 26 and 28 of the relay 35 switch.

An ignition trip mechanism is associated with the relay switch and comprises a magnet 30, an

- armature 32 which constitutes also a contact and a cooperating contact 24. The contact N is 40 mounted on a spring 35 with which one of the contacts 18 is associated and which has an extension 21 to coact with a bridging member 38 of the contacts I! and 20. n

The contacts 18 and 20 are in series and one i set only of them need be provided, but the arrangement shown is used in order to eliminate pig-tail connections.

The lock-out switch of my control apparatus has normally closed contacts I! which may be opened by a spring urged cam ll when it is re leased by a bimetal latch 40.

7 Practical operation In the operation of my control apparatus, the 56 2 ace-acct The starting circuit may be traced in Figure 9 from the lower end of the secondary coil of a transformer 9, which supplies low voltage current for the various control circuits, through the terminal R, wire a, the room thermostat R. T.,

wire b including terminal R and then through the coil 28 of the relay and wire 11 to a lock-out switch heater Q2 and return through wires e and f to the upper end of the secondary coil of the transformer, going through the normally closed startingcontacts it of the combustion switch.

This causes the armature iii of the relay switch to be attracted and the look-out switch heater 42 to start heating. Attraction of the armature |$l closes the motor contacts 8 and 2|? for energizing the burner motor through wires g, h, i, and y and leaves the ignition contacts it closed, the ignition circuit then being traceable through wires 9, h and i and wires k, l and m and through the motor contacts |8 and 26, which upon closing,.;

energize the ignition circuit.

The normal tendency for the ignition contacts I6 is to open when the relay is energized, but they are held closedby the armature 32 of the ignition trip mechanism.

In case combustion does not occur, the heat dissipated from the lock-out switch heater 32 will, after a time period, trip the lock-out switch so that the burner is shut down until the trouble is remedied and the lock-out switch reset manually. If combustion does occur however, the contacts I will be opened, as in Figure 2, thus cutting the look-out switch heater 42 out of circuit.

Running circuit Attraction of the armature l9 also closes the holding contacts 22 whereupon the current flowing from wire b into the right end of the coil 28 of the relay will flow out of the left send of the coil 26, through wires 12 and 0 and then through the contacts 22 and wire p back to the upper end of the secondary coil of the transformer.

Ignition and trip circuit This circuit may be traced from the terminal R and wire 11 through the contacts 34 and 32,

through the magnet 30 and wire q and then' through the contacts l2 of the combustion switch and wire I to the transformer. The contacts l2 are closedwhn combustion occurs, as illustrated,

- in Figure 2. Closing of these contacts energizes to open and the ignition and trip circuit to be opened because of the contacts 32 and 34 being separated.

Combustion causes the combustion switch to move further from the position of Figure 2 to the position of Figure 3 which swings the frictionally mounted arm 2| downwardly, thus keeping the contacts l4 open during the entire movement of the combustion switch from cold to hot position. On the return movement, as in Figures 4, 5 and 6 however, it will be noted that the contacts I2 are first opened so that they are in position for initial operation and then the contacts I are closed, whereafter the contacts it close for initial operation. Finally the positionof Figure. 1 is assumed wherein the contacts M are disengaged.

Safety trip circuit switch, lock-out switch heater and combustion switch so that the return movement of the combustion switch to normal position has no effect.

Incase of combustion failure after it is once established however, it is desirable in a lock-out type of .control apparatus to operate the lock-out switch and this is accomplished by the safety trip contacts Id and a magnet 33. When the position of Figure 5 is assumed by the combustion switch, the contacts M are engaged whereupon current flows through wires a, b, d, r, s, o and p and through R. T., 28, the magnet 53 and contacts 22 cause the magnet to attract the bimetal latch Alli and immediately operate the look-out switch .so that it will have to be manually reset.

The particular frictional mounting of the arm 2| of the combustion switch provides that the contacts It will remain open during the entire movement of the combustion switch from cold to hot position so that the safety trip magnet 43 does not become energized. It becomes energized heretofore used in switches. Essentially the actuating element Ila causes the frictionally mounted arm 2! to move in a direction for engaging the contacts M, the contacts l2 first engaging each other and then the arm on which the lower contact I2 is mounted engaging the arm 2| to cause such movement, as shown in Figure 2. The element |1a then engages the arm 2la to move the lower contact l4 in a separating direction so that during the downward movement of the actu: ator "a, the contacts I 4 do not become engaged.

When theelement I la moves hran opposite direction, however, the contacts I4 are first permitted to engage as in Figure 5 and then the arm 2| is engaged, as in Figure 6, whereafter as in Figure 1, the contacts l4 are separated. Thus 'it is possible to maintain an open circuit throughcontacts l4 when the actuator moves in one direction and both close andopen such circuit when the actuator moves inan opposite direction.

Some changes may be made in the construction and arrangement'of the parts of my device with out departing from the real spirit and purpose of my invention, and it is my intention to cover by my claims, any modified forms of structure or use of mechanical equivalents, which may be rea sonably included within their scope. I claim as my invention:

1. In a control system for a fluid fuel burner and its fuel feeding means; a control circuit in: cluding an igniter, a 'motor for controlling fuel feed, a multiple contact relay operable when energized to close contacts energizing said motor and igniter and to urge contacts controlling energization of said igniter, which are closed when said relay is de-energized, towards open position,

an electrically operable latch mechanism holding said ignition contacts closed when de-energized and a combustion responsive switching mechanism having contacts which are closed upon the establishment of combustion controlling ener gization of said latch mechanism.

2. In a control system for a fluid fuel burner and its fuel feeding means; a control circuit including an igniter, a motor for controlling fuel feed, a multiple contact relay operable when energized to close contacts energizing said motor and igniter and to urge contacts controlling energization of said igniter, which are closed when said relay is de-energized, towards open position, an electrically operable latch mechanism holding said ignition contacts closed when de-energized and a combustion responsible switching mechanism having contacts which are closed upon the establishment of combustion controlling ener-v gization of said latch mechanism. said electrically operable latch mechanism including a pair of contacts in the circuit of the mechanism and operable to separated position upon energization of the mechanism.

3. In a control system for a fluid fuel burner and its fuel feeding means, a control circuit including an igniter, a motor for controlling fuel feed, a lock-out switch, a multiple contact relay operable when energized to close contacts energizing said motor and igniter and to urge contacts controlling energization of said igniter, which are closed when said relay is de-energized, toward open position, electrically operable actuating means for said lock-out switch, an electrically operable latch mechanism holding said ignition contacts closed when de-energized and a combustion responsive switching mechanism having contacts which are closed upon the establishment of combustion, controlling energization of said latch mechanism and contacts which are open before combustion is established and remain open while it is being and after it is established and which are closed only upon subsequent failure of combustion, said last mentioned contacts controlling energization of said actuating means.

4. In a control system for a fluid fuel burner and its fuel feeding means, a control circuit including an igniter, a motor for controlling fuel feeding, a lock-out switch, a multiple contact relay operable when energized to close contacts energizing said motor and igniter and to urge contacts controlling energization of said igniter which are closed when said relay is de-energized, toward open position, delayed action actuating means for tripping said lock-out switch and an electro-magnet for also tripping it quickly when energized, an electrically operable latch mechanism holding said ignition contacts closed when de-energized and a combustion responsive switching mechanism having contacts which are closed upon the establishment of combustion, controlling energization of said latch mechanism, other contacts opened upon the establishment of combustion effecting de-energization of said delayed action actuating means and still other contacts which are open before combustion is established and remain open while it is being and after it is established, and which are closed only upon subsequent failure of combustion, said last mentioned contacts controlling energization of said electromagnet.

5. In a control system for a fluid fuel burner, and its fuel feeding means, a control circuit including a motor for controlling fuel feed, a lockout switch, a multiple contact relay operable when energized to close contacts energizing said motor, electrical actuating means operable when energized to immediately open said lock-out switch, and a combustion responsive switching mechanism having contacts which are open before combustion is established and remain open while it is being and after it is established and which are closed only upon subsequent failure of combustion, said last mentioned contacts controlling energization of said actuating means.

6. In a control system for a fluid fuel burner and its fuel feeding means, a control circuit including a motor for controlling fuel feeding, a lock-out switch, a multiple contact relay operable when energized to close contacts energizing said motor, delayed action actuating means for tripping said lock-out switch and an electro-magnet for also tripping it quickly when energized, and

a combustion responsive switching mechanism havin contacts closed upon the establishment of combustion effecting de-energization of said delayed action actuating means and other contacts which are open before combustion is established and remain open while it is being and after it is 

